Heat-curable silicone compositions having improved bath life

ABSTRACT

A curable organosilicon composition comprises a component having silicon-bonded hydrogen atoms, a component having silicon-bonded radicals reactive therewith, a curing catalyst, a catalyst-inhibitor and a bath life extender. The use of certain compounds, which are ineffective as a bath life extender in the absence of a catalyst inhibitor, effectively extend the room temperature bath life of a silicone coating composition containing a catalyst inhibitor. Being a substantial non-inhibitor for the catalyst the bath life extender component does not effect the cure time and/or cure temperature of the composition. 
     This discovery has permitted the preparation of curable coating compositions which have a long bath life at room temperature and a rapid cure time at elevated temperatures which does not drift to longer intervals as the coating compositions ages over a typical production run. 
     The room temperature cure times of the organopolysiloxane coating compositions of this invention are adequately long, and their cure times at elevated temperature are advantageously brief, that they are useful in fast-paced coating operations, such as adhesive release coating operations wherein the cured coating is further coated with an adhesive in-line, i.e., immediately after being cured.

This is a divisional of copending application Ser. No. 07/431,352 filedon Nov. 3, 1989, now U.S. Pat. No. 5,036,117.

BACKGROUND OF THE INVENTION

The present invention relates to improved compositions which cure by wayof a precious metal-catalyzed reaction of silicon-bonded radicals andhave an improved bath life. The present invention further relates to animproved process for using said compositions.

Organosilicon compositions in which a platinum group metal-containingcatalyst is inhibited in its cure-promoting activity at room temperatureby the presence of a catalyst inhibitor are well known in theorganosilicon art and need no detailed discussion herein.

Among the many inhibitors of the art the maleate inhibitors of U.S. Pat.Nos. 4,256,870 and 4,562,096, and the fumarate inhibitors of U.S. Pat.No. 4,774,111, are of particular concern.

The maleates have been found to be particularly effective for increasingthe room temperature bath life, i.e. work time, of solventless coatingorganosilicon compositions which cure by way of a platinum groupmetal-catalyzed reaction. However, the heating time and/or temperatureneeded to cure these maleate-inhibited compositions are/is sometimesexcessive. When one attempts to decrease the cure time and/ortemperature of these compositions to a commercially desirable intervalby using less maleate and/or more catalyst the bath life is frequentlydecreased to a commercially undesirable interval.

The fumarate inhibitors have been found to allow a cure of a solventlesscoating organosilicon compositions which cure by way of a platinum groupmetal-catalyzed reaction to take place at a suitable heating time and/ortemperature. However, the bath life of such a composition, as measuredby gel time at room temperature, is not as long as desired. When oneattempts to increase the bath life of these compositions by increasingthe amount of fumarate and/or decreasing the amount of catalyst the curetime and/or temperature increases.

This problem of increased cure time and/or cure temperature withincreased bath life in an inhibited platinum group metal-catalyzedsystem is of particular significance for applications where theorganosilicon composition is used to rapidly coat a substrate over along period of time. In such a process a long bath life coupled with ashort cure time, preferably at low-to-moderate temperature, is anessential property of the coating composition.

In the coating arts, such as the paper coating art, the coatingcomposition that is used to coat a substrate should not cure to theextent that its viscosity has increased substantially before it has beenapplied to the substrate; however, it should rapidly cure thereafter,preferably with only a moderate amount of added energy. Typically thismeans that the coating compositions preferably should not gel for aslong as eight hours but should cure rapidly at moderately increasedtemperature to such an extent that the coated substrate can be furtherprocessed, if desired, without damaging the coating. In addition, thecure time of the composition at a given cure temperature desirablyshould remain substantially constant as the bath ages.

In the preparation of laminates comprising a peelable release paperbearing a cured coating and an adhesive film releasably adhered thereto,such as a stick-on label, one of two processes is normally used. In oneprocess, the off-line process, the silicone composition is coated onpaper and cured; then, at a later time, an adhesive film is applied tothe cured silicone coating. In the other process, the in-line process,the silicone composition is applied to paper and cured and the adhesiveis then immediately coated on the cured silicone coating. While thein-line process is generally more efficient and would normally be moreadvantageous, it has been found that some adhesives bond, i.e. weld, tothe silicone coated paper if the adhesive is applied to the siliconecoated paper within a short time after the silicone composition has beencured. It is believed that residual reactivity in the cured siliconecoating is responsible for the welding of the silicone and adhesive inthe in-line process.

While the art has proposed and provided some solutions for the weldingproblem there is a need for further improvements in a release-coatingcomposition for in-line lamination of adhesives which cures at lowertemperature and/or has a longer bath life.

There is also interest in applying silicone release coatings tosubstrates, such as polyethylene sheets, which are less stable at theelevated temperatures used to cure the silicone release coatings of theart. Consequently there is a need for silicone coatings which cure atreduced temperatures. Of course, silicone coatings which have lowercuring temperatures or faster curing rates are also desired for energyconservation and for more efficient production processes.

BRIEF SUMMARY OF THE INVENTION

It is an object of this invention to provide improved curableorganosilicon compositions. It is also an object of this invention toprovide organopolysiloxane compositions which do not cure at roomtemperature for long periods of time but which cure rapidly when heatedto moderately elevated temperatures and/or irradiated with actinicradiation. It is an additional object of this invention to providecurable coating compositions and a process for preparing adhesiverelease liners. It is a further object of this invention to provide away to control the cure of a platinum group metal-catalyzedorganopolysiloxane composition so as to provide for the composition ashort cure time at moderately elevated temperatures which does notdrift, i.e., change, as the curable composition ages at roomtemperature.

These objects, and others which will occur to one of ordinary skill inthe curable organosilicon composition art upon considering the followingdisclosure and appended claims, are obtained by the present inventionwhich, briefly stated, comprises a curable organosilicon compositioncomprising a component having silicon-bonded hydrogen atoms, a componenthaving silicon-bonded hydroxyl and/or olefinic hydrocarbon radicalsreactive therewith, a platinum group metal-containing catalyst, and acure-control component comprising an inhibitor component and a bath lifeextender component, said components hereinafter being delineated. In apreferred embodiment the inhibitor component is used in an amount whichis insufficient, by itself, to provide adequate bath life for thecomposition; however, in the presence of the bath life extendercomponent an adequate bath life is obtained.

According to the present invention it has been surprisingly discoveredthat the use of certain compounds, which are ineffective by themselvesas a bath life extender in the absence of a catalyst inhibitor,effectively extend the room temperature bath life of a platinum groupmetal-catalyzed silicone coating composition containing a catalystinhibitor. Being a substantial non-inhibitor for the metal-containingcatalyst the bath life extender component does not effect the curingbehavior of the composition at elevated temperature. Thus, incombination, the inhibitor component and the bath life extendercomponent regulates the heat-curing of the composition and its roomtemperature stability.

This discovery has permitted the preparation of curable coatingcompositions which not only have improved bath life but, unexpectedly,have the stable cure profile of the hydrocarbonoxyalkylmaleate-inhibited compositions of U.S. Pat. No. 4,562,096. That is tosay, the compositions of the present invention possess long bath livesat room temperature and a rapid cure time at elevated temperatures whichdoes not drift, i.e. change to a different cure time, as the coatingcompositions ages over a typical production run.

The room temperature cure times of the coating compositions of thisinvention are adequately long, and their cure times at elevatedtemperature are advantageously brief, that they are useful in fast-pacedcoating operations, such as adhesive release coating operations whereinthe cured coating is further coated with an adhesive in-line, i.e.,immediately after being cured.

While not limiting the present invention with any particular theory, webelieve that the bath life extender component provides its benefits bybecoming loosely associated with, and forming a protective layer around,a catalyst/inhibitor complex. One theory for this protective actionproposes a micelle-type construction wherein the catalyst/inhibitorcomplex is surrounded by a layer of bath life extender molecules in amanner which results in a more complete blocking of availablecoordination sites on the catalyst/inhibitor complex at roomtemperature, thereby delaying a reaction of silicon-bonded hydrogenatoms with silicon-bonded hydroxy or olefinic hydrocarbon radicalsand/or, when reaction does take place, delaying the departure ofreaction products from the catalyst/inhibitor complex. In fact, the mosteffective materials to be used as the bath life extender component inthe compositions of this invention are non-inhibitors for a platinumgroup metal-containing catalyst, especially the below-noted preferredcomplex of chloroplatinic acid and a vinylsiloxane. At elevatedtemperatures the loosely associated bath life extender molecules arethought to be easily disassociated from the catalyst/inhibitor complex.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a curable composition comprising (A) anorganosilicon compound having an average of at least two curing radicalsper molecule thereof selected from the group consisting of the hydroxyradical and olefinic hydrocarbon radicals, (B) an organohydrogensiliconcompound containing an average of at least two silicon-bonded hydrogenatoms per molecule thereof, the amounts of Components (A) and (B) beingsufficient to provide a ratio of the number of silicon-bonded hydrogenatoms to the number of silicon-bonded curing radicals of from 1/100 to100/1, (C) a platinum group metal-containing catalyst in sufficientamount to accelerate a curing reaction among said silicon-bonded curingradicals and said silicon-bonded hydrogen atoms, (D) an inhibitorcompound for said accelerated curing reaction in a total amountsufficient to retard the curing reaction at room temperature butinsufficient to prevent said reaction at elevated temperature, and (E) abath life extender compound in a total amount sufficient to furtherretard the curing reaction at room temperature.

Herein the term "curable", as applied to compositions of this invention,generally denotes a chemical change which leads to a change in the stateof the composition from a liquid to a solid. For coating compositions ofthis invention which are to be used as adhesive-release coatings theterm "curable" has a more detailed meaning which encompasses the absenceof smear, migration and rub-off of the coating, as delineated below.

The curing of the compositions of this invention is accomplished by areaction between silicon-bonded hydroxy and/or olefinic hydrocarbonradicals in Component (A) and silicon-bonded hydrogen atoms in Component(B). The curing of the compositions of this invention is controlled bythe platinum group metal-containing catalyst Component (C), theinhibitor Component (D) and the bath life extender Component (E). Thesecomponents are delineated as follows.

Component (A) of the compositions of this invention can be anyorganosilicon compound containing at least one silicon atom and from 1to 4 silicon-bonded monovalent radicals per silicon; with the provisothat the organosilicon compound contains at least two silicon-bondedcuring radicals selected from the hydroxy radical and olefinichydrocarbon radicals. This component can be a solid or a liquid havingany viscosity, such as a freely flowing, gum-like material or ahydrocarbon-soluble resin.

Multiple silicon atoms in Component (A) are linked by divalent radicalswhich include oxygen atoms, which provide siloxane bonds, andaliphatically saturated hydrocarbon, hydrocarbon ether, halohydrocarbonether and halohydrocarbon radicals which provide silcarbane bonds. Thedivalent radicals in Component (A) can be the same or different, asdesired. Preferred divalent hydrocarbon radicals are 1-20 carbon atomalkylene radicals.

The monovalent radicals in Component (A) can contain up to 20 carbonatoms and include halohydrocarbon radicals free of aliphaticunsaturation, hydrocarbon radicals and hydroxy radicals.

Monovalent hydrocarbon radicals include alkyl radicals, such as methyl,ethyl, propyl, butyl, hexyl and octyl; cycloaliphatic radicals, such ascyclohexyl; aryl radicals, such as phenyl, tolyl and xylyl; aralkylradicals, such as benzyl and phenylethyl; and olefinic hydrocarbonradicals, such as vinyl, allyl, methallyl, butenyl, hexenyl, octenyl,cyclohexenyl and styryl. Alkenyl radicals are preferably terminallyunsaturated. Of the higher alkenyl radicals those selected from thegroup consisting of 5-hexenyl, 7-octenyl, and 9-decenyl are preferredbecause of the more ready availability of the alpha, omega-dienes thatcan be used to prepare the alkenylsiloxanes. Highly preferred monovalenthydrocarbon radical for the silicon-containing components of thecompositions of this invention are methyl, phenyl, vinyl and 5-hexenyl.

Monovalent halohydrocarbon radicals free of aliphatic unsaturationinclude any monovalent hydrocarbon radical noted above which is free ofaliphatic unsaturation and has at least one of its hydrogen atomsreplaced with halogen, such as fluorine, chlorine or bromine. Preferredmonovalent halohydrocarbon radicals have the formula C_(n) F_(2n+1) CH₂CH₂ --wherein the subscript n has a value of from 1 to 10, such as, forexample, CF₃ CH₂ CH₂ -- and C₄ F₉ CH₂ CH₂ --.

Component (A) of the compositions of this invention is typically anorganopolysiloxane having the average unit formula R_(c) ²SiO.sub.(4-c)/2 wherein R² denotes said monovalent radical, delineatedand limited above, and the subscript c has a value of from 1 to 3, suchas 1.0, 1.2, 1.9, 2.0, 2.1, 2.4 and 3.0. The organopolysiloxanes havingthe above average unit formula contain siloxane units having theformulae R₃ ² SiO_(1/2), R₂ ² SiO_(2/2), R² SiO_(3/2) and SiO_(4/2).Said siloxane units can be combined in any molecular arrangement such aslinear, branched, cyclic and combinations thereof, to provideorganopolysiloxanes that are useful as Component (A).

A preferred organopolysiloxane Component (A) for the composition of thisinvention is a substantially linear organopolysiloxane having theformula XR₂ SiO(XRSiO)_(x) SiR₂ X. By the term "substantially linear" itis meant that the component contains no more than trace amounts ofsilicon atoms bearing 3 or 4 siloxane linkages or silicon atoms bearingmore than 1 hydroxy radical but up to about 15 percent by Weightcyclopolydiorganosiloxanes which are frequently co-produced with thelinear organopolysiloxanes.

In the formula shown immediately above each R denotes a monovalenthydrocarbon or halohydrocarbon radical free of aliphatic unsaturationand having from 1 to 20 carbon atoms, as exemplified above. The severalR radicals can be identical or different, as desired. Independently,each X denotes hydroxy, R or an olefinic hydrocarbon radical having from2 to 20 carbon atoms, as exemplified above. Of course, at least two Xradicals are hydroxy or olefinic hydrocarbon radicals. For the coatingcompositions and process of this invention X is preferably an olefinichydrocarbon radical and at least 50 percent of all R radicals aremethyl.

The value of the subscript x in the above formula is such that thelinear organopolysiloxane (A) has a viscosity at 25° C. of at least 25millipascal-seconds (25 centipoise). The exact value of x that is neededto provide a viscosity value meeting said limit depends upon theidentity of the X and R radicals; however, for hydrocarbyl-terminatedpolydimethylsiloxane x will have a value of at least 25.

In terms of preferred monovalent hydrocarbon radicals, noted above,examples of linear organopolysiloxanes of the above formula which aresuitable as Component (A) for the composition of this invention includeHO{Me(CF₃ CH₂ CH₂)SiO}_(x) H, HO(Me₂ SiO)_(x) H, HO{(Me₂ SiO)₀.9(MeViSiO)₀.1 }_(x) H, ViMe₂ SiO(Me₂ SiO)_(x) SiMe₂ Vi, HexMe₂ SiO(Me₂SiO)_(x) SiMe₂ Hex, HexMe₂ SiO(Me₂ SiO)₀.95x (MeHexSiO)₀.05x SiMe₂ Hex,Me₃ SiO(Me₂ SiO)₀.9x (MeViSiO)₀.1x SiMe₃, ViMe₂ SiO(Me₂ SiO)₀.95x(MeViSiO)₀.05x SiMe₂ Vi, Me₃ SiO(Me₂ SiO)₀.9x (MeHexSiO)₀.1x SiMe₃, andPhMeViSiO(Me₂ SiO)₀.93x (MePhSiO)₀.07x SiPhMeVi wherein Me, Vi, Hex andPh denote methyl, vinyl, 5-hexenyl and phenyl, respectively.

For coating composition of this invention it is highly preferred thatthe linear organopolysiloxanes (A) have the formula XMe₂ SiO(Me₂SiO)_(b) (MeXSiO)_(d) SiMe₂ X wherein X is as noted above and the sum ofthe subscripts b plus d is equal to x, also noted above. The values ofthe subscripts b and d can each be zero or greater; however, the valueof d is typically less than 10% of the value of b.

In a preferred embodiment of the present invention, wherein the curablecomposition is used to coat a solid substrate, such as paper, with anadhesive-releasing coating, the value of b plus d in the highlypreferred organopolysiloxane (A) is sufficient to provide a viscosity at25° C. for the Component (A) of at least 100 mPa.s, such as from about100 mPa.s to about 100 Pa.s, preferably from about 100 mPa.s to 10 Pa.sand, most preferably, from 100 mPa.s to 5 mPa.s; said viscositiescorresponding approximately to values of B+d of at least 60, such asfrom 60 to 1000, preferably 60 to 520 and, most preferably, 60 to 420,respectively. In addition, the value of subscript d is preferablylimited to less than 0.1 b as noted above.

Component (B) of the compositions of this invention can be anyorganohydrogensilicon compound which is free of aliphatic unsaturationand contains two or more silicon atoms linked by divalent radicals, anaverage of from one to two silicon-bonded monovalent radicals persilicon atom and an average of at least two, and preferably three ormore, silicon-bonded hydrogen atoms per molecule thereof. PreferablyComponent (B) contains an average of three or more silicon-bondedhydrogen atoms such as, for example, 5, 10, 20, 40 and more.

Divalent radicals linking silicon atoms in Component (B) are asdelineated above for Component (A), including preferred examples. Aswith Component (A), the divalent radicals within Component (B) can beidentical or different, as desired. Furthermore, the divalent radicalsthat are present in Component (B) can, but need not, be the same as thedivalent radicals that are present in Component (A).

Monovalent radicals in Component (B) include monovalent hydrocarbon andhalohydrocarbon radicals free of aliphatic unsaturation, as delineatedabove for Component (A), including preferred examples. The monovalentradicals that are present in Component (B) are preferably, but need notbe, the same as the monovalent radicals that are present in Component(A).

Component (B) of the compositions of this invention is anorganohydrogenpolysiloxane having the average unit formula R_(e) ³ H_(f)SiO.sub.(4-e-f)/2 wherein R³ denotes said monovalent radical free ofaliphatic unsaturation, the subscript f has a value of from greater than0 to 1, such as 0.001, 0.01, 0.1 and 1.0, and the sum of the subscriptse plus f has a value of from 1 to 3, such as 1.2, 1.9 and 2.5. Siloxaneunits in the organohydrogenpolysiloxanes having the average unit formulaimmediately above have the formulae R₃ ³ SiO_(1/2), R₂ ³ HSiO_(1/2), R₂³ SiO_(2/2), R³ HSiO_(2/2), R³ SiO_(3/2), HSiO_(3/2) and SiO_(4/2). Saidsiloxane units can be combined in any molecular arrangement such aslinear, branched, cyclic and combinations thereof, to provideorganohydrogenpolysiloxanes that are useful as Component (B).

A preferred organohydrogenpolysiloxane Component (B) for thecompositions of this invention is a substantially linearorganohydrogenpolysiloxane having the formula YR₂ SiO(YRSiO)_(y) SiR₂ Ywherein each R denotes a monovalent hydrocarbon or halohydrocarbonradical free of aliphatic unsaturation and having from 1 to 20 carbonatoms, as exemplified above. The several R radicals can be identical ordifferent, as desired. Additionally, each Y denotes a hydrogen atom oran R radical. Of course, at least two Y radicals must be hydrogen atoms.The value of the subscript y is not critical; however, for the coatingcompositions and process of this invention, it is preferably such thatthe organohydrogenpolysiloxane Component (B) has a viscosity at 25° C.of up to 100 millipascal-seconds. The exact value of y needed to providea viscosity value falling within said limits depends upon the number andidentity of the R radicals; however, for organohydrogenpolysiloxanescontaining only methyl radicals as R radicals y will have a value offrom about 0 to about 100.

In terms of preferred monovalent hydrocarbon radicals noted above,examples of organopolysiloxanes of the above formulae which are suitableas Component (B) for the compositions of this invention include HMe₂SiO(Me₂ SiO)_(y) SiMe₂ H, (HMe₂ SiO)₄ Si, cyclo-(MeHSiO)_(y), (CF₃ CH₂CH₂)MeHSiO{Me(CF₃ CH₂ CH₂) SiO}_(y) SiHMe(CH₂ CH₂ CF₃), Me₃SiO(MeHSiO)_(y) SiMe₃, HMe₂ SiO(Me₂ SiO)₀.5y (MeHSiO)₀.5y SiMe₂ H, HMe₂SiO(Me₂ SiO)₀.5y (MePhSiO)₀.1y (MeHSiO)₀.4y SiMe₂ H, Me₃ SiO(Me₂SiO)₀.3y (MeHSiO)0.7ySiMe₃ and MeSi(OSiMe₂ H)₃.

Highly preferred linear organohydrogenpolysiloxane (B) for the coatingcompositions of this invention have the formula YMe₂ SiO(Me₂ SiO)_(p)(MeYSiO)_(q) SiMe₂ Y wherein Y denotes a hydrogen atom or a methylradical. As noted above, an average of at least two Y radicals permolecule of Component (B) must be hydrogen atoms. The subscripts p and qcan have average values of zero or more and the sum of p plus q has avalue equal to y, noted above. The disclosure of U.S. Pat. No. 4,154,714is incorporated herein by reference to show highly-preferredorganohydrogenpolysiloxanes.

The amounts of Components (A) and (B) that are used in the compositionsof this invention are not narrowly limited. Said amounts, expressed interms of the ratio of the number of silicon-bonded hydrogen atoms ofComponent (B) to the number of silicon-bonded hydroxy and/or olefinichydrocarbon radicals of Component (A), are sufficient to provide a valueof from 1/100 to 100/1 for said ratio, usually from 1/2 to 20/1, andpreferably from 1/2 to 2/1. For the liquid coating compositions of thisinvention which are to be used in the coating method of this invention,hereinbelow delineated, the value of said ratio should have a value offrom 1/2 to 2/1. and preferably about 1/1.

Organosilicon polymers are, of course, well known in the organosiliconart. Their preparation is well documented and needs no intensivedelineation herein. Organopolysiloxanes are clearly the most significantand most widely used form of organosilicon polymers in the art, and inthis invention; many are commercially prepared.

Briefly, organopolysiloxanes are typically prepared by way of hydrolysisand condensation of hydrolyzable silanes such as Me₂ SiCl₂, Me₃ SiCl,MeSiCl₃, SiCl₄, Me₂ Si(OMe)₂, MeSi(OMe)₃ and Si(OCH₂ CH₃)₄ or by way ofacid- or alkalicatalyzed siloxane equilibration of suitable siloxaneprecursors such as cyclo-(Me₂ SiO)₄ and Me₃ SiOSiMe₃, which themselvesare prepared by way of said hydrolysis and condensation reactions.

Organosilicon polymers having both silcarbane and siloxane structure canbe prepared, for example, from monomeric species that have non-oxygendivalent radicals, such as O_(1/2) Me₂ SiCH₂ CH₂ Me₂ SiO_(1/2) or ClMe₂SiC₆ H₄ SiMe₂ Cl, using standard hydrolysis and condensation reactions,noted above, and incorporating one or more of the olefinic hydrocarbonradicals or hydrogen atom-containing silanes or siloxanes noted above,and other silanes or siloxanes, as desired.

Organosilicon polymers which contain no siloxane bonds can be prepared,for example, by a hydrosilylation reaction between silanes orsilcarbanes bearing silicon-bonded olefinically unsaturated hydrocarbonradicals, such as Vi₂ SiMe, or ViMe₂ SiC₆ H₄ SiMe₂ Vi and silanes orsilcarbanes bearing silicon-bonded hydrogen atoms, such as H₂ SiMe₂ orHMe₂ SiC₆ H₄ SiMe₂ H.

Other suitable methods for preparing the organosilicon components thatare used in the compositions of this invention also occur in theorganosilicon art.

Organopolysiloxane Component (A) containing olefinic hydrocarbonradicals can be prepared as noted above with the proviso that a silaneor siloxane containing at least one silicon-bonded olefinic hydrocarbonradical is used, alone or in conjunction with other silanes orsiloxanes, in sufficient amount to provide the necessary number ofolefinic hydrocarbon radicals in the organopolysiloxane. Examples ofolefinic hydrocarbon radical-containing silanes or siloxanes include,but are not limited to, ViMe₂ SiCl, HexMe₂ SiCl, MeViSiCl₂, MeHexSiCl₂,ViSiCl₃, HexSiCl₃, (MeViSiO)₄, HexMe₂ SiOSiMe₂ Hex and ViMe₂ SiOSiMe₂Vi.

It is usually preferred to prepare olefinic siloxanes by hydrolyzing areadily hydrolyzable silane, such as 5-hexenyl- orvinyl-methyldichlorosilane, in excess water and then equilibrating theresulting hydrolyzate with cyclopolydimethylsiloxanes and a siloxaneoligomer containing triorganosiloxane end groups, using a base catalystsuch as KOH. However, it is believed that olefinic polydiorganosiloxanesmay also be advantageously prepared in a one-step acid-catalyzed processwherein the hydrolyzable silane is hydrolyzed and simultaneouslyequilibrated with cyclopolydimethylsiloxanes and siloxane oligomercontaining end groups.

Alternatively, known polyorganohydrogensiloxanes bearing reactive SiHgroups can be reacted with an alpha, omega-diene, such as 1,5-hexadiene,to prepare higher alkenyl-substituted organopolysiloxanes. It should benoted that linear siloxanes produced by equilibration procedures maycontain small amounts, such as 0 to 15 weight percent, ofcyclopolydiorganosiloxanes which may be volatile at temperatures up to150° C. For the purposes of this invention either siloxanes that stillcontain the small amounts of cyclics or siloxanes from which theco-produced cyclics have been removed by volatilization may be used.

Organohydrogenpolysiloxane Component (B) can be prepared as noted abovewith the proviso that a silane or siloxane containing at least onesilicon-bonded hydrogen atom, instead of olefinic hydrocarbon radical,is used, alone or in combination with other silanes or siloxanes, insufficient amount to provide the necessary number of silicon-bondedhydrogen atoms in the organohydrogenpolysiloxane. Examples of hydrogenatom-containing silanes or siloxanes include, but are not limited to,HMe₂ SiCl, HMeSiCl₂, HSiCl₃, HMe₂ SiOSiMe₂ H and cyclo-(MeHSiO)₄.Component (B) is preferably prepared under non-alkaline conditions tominimize cleavage of Si-H linkages.

Component (C) of the composition of this invention can be any platinumgroup metal-containing catalyst component which facilitates the reactionof the silicon-bonded hydrogen atoms of Component (B) with thesilicon-bonded hydroxy and/or silicon-bonded olefinic hydrocarbonradicals of Component (A). By platinum group it is meant hereinruthenium, rhodium, palladium, osmium, iridium and platinum.

Component (C) is preferably a platinum-containing catalyst componentsince they are most widely used and available and because they provide amore favorable effect for the compositions of this invention in terms ofimproved pot life and/or cure time, as hereinafter discussed.Platinum-containing catalysts can be platinum metal, optionallydeposited on a carrier, such as silica gel or powdered charcoal; or acompound or complex of a platinum group metal. A preferredplatinum-containing catalyst component in the compositions of thisinvention is a form of chloroplatinic acid, either as the commonlyavailable hexahydrate form or as the anhydrous form, as taught bySpeier, U.S. Pat. No. 2,823,218, incorporated herein by reference.Because of its easy dispersibility in organosilicon systems aparticularly useful form of chloroplatinic acid is that compositionobtained when it is reacted with an aliphatically unsaturatedorganosilicon compound such as divinyltetramethyldisiloxane, asdisclosed by Willing, U.S. Pat. No. 3,419,593, incorporated herein byreference. Other platinum catalysts which are thought to be useful inthe present invention include those disclosed in U.S. Pat. Nos.3,159,601; 3,159,602; 3,220,972; 3,296,291; 3,516,946; 3,814,730 and3,928,629, incorporated herein by reference.

The amount of platinum group metal-containing catalyst component that isused in the compositions of this invention is not narrowly limited aslong as there is a sufficient amount to accelerate a room temperaturereaction between the silicon-bonded hydrogen atoms of Component (B) withthe silicon-bonded hydroxy and/or olefinic hydrocarbon radicals ofComponent (A) and not so much as to make its action uncontrollable bythe use of Components (D) and (E), delineated below. The exact necessaryamount of this catalyst component will depend upon the particularcatalyst and is not easily predictable. However, for platinum-containingcatalysts the amount can be as low as one part by weight of platinum forevery one million parts by weight of organosilicon Component (A).Preferably said amount is at least 10 parts by weight, on the samebasis. For compositions of this invention which are to be used in thecoating method of this invention the amount of platinum-containingcatalyst component to be used is sufficient to provide from 50 to 500,preferably 100 to 300, parts by weight platinum per one million parts byweight of organopolysiloxane Component (A).

Component (D) of the compositions of this invention is any material thatis known to be, or can be, used as an inhibitor for the catalyticactivity of platinum group metal-containing catalysts. By the term"inhibitor" it is meant herein a material that retards the roomtemperature curing of a curable mixture of Components (A), (B), and (C),when incorporated therein in small amounts, such as less than 10 percentby weight of the composition, without preventing the elevatedtemperature curing of the mixture. Of course, it is known thatmaterials, such as hydrocarbons, which are not inhibitors when used insmall amounts have an inhibiting effect when used in solvent amounts,such as from 35 to 95% by weight. These materials are not consideredinhibitors for the purposes of this invention.

Inhibitors for the platinum group metal catalysts are well known in theorganosilicon art. Examples of various classes of such metal catalystinhibitors include unsaturated organic compounds such as ethylenicallyor aromatically unsaturated amides, U.S. Pat. No. 4,337,332; acetyleniccompounds, U.S. Pat. Nos. 3,445,420 and 4,347,346; ethylenicallyunsaturated isocyanates, U.S. Pat. No. 3,882,083; olefinic siloxanes,U.S. Pat. No. 3,989,667; unsaturated hydrocarbon diesters U.S. Pat. Nos.4,256,870; 4,476,166 and 4,562,096, and conjugated ene-ynes, U.S. Pat.Nos. 4,465,818 and 4,472,563; other organic compounds such ashydroperoxides, U.S. Pat. No. 4,061,609; ketones, U.S. Pat. No.3,418,731; sulfoxides, amines, phosphines, phosphites, nitriles, U.S.Pat. No. 3,344,111; diaziridines, U.S. Pat. No. 4,043,977; and varioussalts, such as U.S. Pat. No. 3,461,185. It is believed that thecompositions of this invention can comprise an inhibitor from any ofthese classes of inhibitors.

Organic inhibitor compounds which bear aliphatic unsaturation and one ormore polar groups, such as carbonyl or alcohol groups, display usefulbath life extension benefits when combined with Component (E) of thepresent invention. Examples thereof include the acetylenic alcohols ofKookootsedes and Plueddemann, U.S. Pat. No. 3,445,420, such asethynylcyclohexanol and methylbutynol; the unsaturated carboxylic estersof Eckberg, U.S. Pat. No. 4,256,870, such as diallyl maleate anddimethyl maleate; and the maleates and fumarates of Lo, U.S. Pat. Nos.4,562,096 and 4,774,111 , such as diethyl fumarate, diallyl fumarate andbis-(methoxyisopropyl) maleate. The half esters and amides of Melanchon,U.S. Pat. No. 4,533,575; and the inhibitor mixtures of Eckberg, U.S.Pat. No. 4,476,166 would also be expected to behave similarly. Theabove-mentioned patents relating to inhibitors for platinum groupmetal-containing catalysts are incorporated herein by reference to teachhow to prepare compounds which are suitable for use as Component D) inour compositions.

Preferred inhibitors for the compositions of this invention are themaleates and fumarates. It has been discovered that the compositions ofthis invention comprising a fumarate inhibitor have long bath lives, inspite of the weak inhibiting effect of the fumarate inhibitor, becauseComponent (E) is included therein. Surprisingly their usual short curetimes are not increased substantially by the presence of Component E).It has also been discovered that the compositions of this inventioncomprising a maleate have short cure times, in spite of the stronginhibiting effect of the maleate inhibitor, because a relatively lowconcentration of maleate can be used when Component (E) is included inthe composition. Surprisingly their long bath lives are not decreased bythis reduction in inhibitor concentration.

The maleates and fumarates that are preferred as Component (D) in thecompositions of this invention have the formula R¹ (OD)_(h) O₂ CCH═CHCO₂(DO)_(h) R¹ wherein R¹ denotes an hydrocarbon radical having from 1 to10 carbon atoms and each D denotes, independently, an alkylene radicalhaving from 2 to 4 carbon atoms. R¹ can be, for example, an alkylradical such as methyl, ethyl, propyl, isopropyl, butyl, pentyl orhexyl; an aryl radical such as phenyl or benzyl; an alkenyl radical suchas vinyl or allyl; alkynyl radicals; or a cyclohydrocarbon radical suchas cyclohexyl. D can be, for example, --CH₂ CH₂ --, --CH₂ (CH₃)CH--,--CH₂ CH₂ CH₂ --, --CH₂ CH₂ CH₂ CH₂ --, --CH₂ (CH₃ CH₂)CH-- and --CH₂CH₂ (CH₃)CH--. The individual R¹ radicals and D radicals of the maleatesand fumarates can be identical or different, as desired. The value ofsubscript h in the formula immediately above can have a value equal tozero or 1. The individual values of h can be identical or different, asdesired. It has been found that for composition of this inventionwherein the organosilicon Component (A) is a linear polydiorganosiloxanebearing olefinic hydrocarbon radicals the fumarates, combined withComponent (E), provide a superior curing action. Diethyl fumarate ispreferred.

The amount of Component (D) to be used in the composition of thisinvention is not known to be critical and can be any amount that willretard the above-described catalyzed reaction at room temperature whilenot preventing said reaction at elevated temperature. No specific amountof inhibitor can be suggested to obtain a specified bath life at roomtemperature since the desired amount of any particular inhibitor to beused will depend upon the concentration and type of the platinum groupmetal-containing catalyst, the nature and amounts of Components (A) and(B) and the presence or absence of optional ingredients. While notwishing to limit the present invention by theory we believe that thereshould be at least on molecule of inhibitor for each platinum groupmetal atom in the composition, to form a room temperature stable complextherebetween. We further believe that there should be at least threemolecules of maleate or fumarate inhibitor for each platinum group metalatom in the composition, to form a room temperature stable complextherebetween. In the liquid organopolysiloxane compositions that areused in the coating method of this invention the amount of inhibitor istypically sufficient to provide from 25 to 50 molecules thereof forevery platinum group metal atom in the composition.

Maleates and fumarates added in small amounts, such as 0.1 weightpercent based on the weight of Component (A), in compositions of thisinvention provide an increased bath life. A practical upper limitappears to be 0.2 percent for a maleate inhibitor and 2.0 percent for afumarate inhibitor, on the same basis noted immediately above, if a curetime at 82° C. of less than 30 seconds is desired. Greater amounts ofmaleates and fumarates can be used if desired; however, drifting or longcure times may result.

Thus, while we have generally taught the broad and narrow limits for theinhibitor component concentration in our compositions the skilled workercan readily determine the optimum level thereof for each system, ifdesired.

Component (E) can be any compound which is effective for extending thebath life of a curable mixture of the above-delineated Components (A),(B), (C) and (D), when incorporated therein according to this invention;but which is ineffective for extending the bath life of the samemixture, absent said Component (D). In other words, Component (E) lacksan inhibiting effect on platinum group metal-containing catalysts byitself, yet increases the bath life of the composition when a platinumgroup metal-containing catalyst inhibitor is present. By the term"inhibiting effect" it is meant the room temperature cure-retardingeffect of an inhibitor, as noted above.

In a preferred embodiment of this invention Component (E) can be anycompound which increases the bath life, but not the 70° C. cure time, ofa platinum-catalyzed composition which contains a fumarate of maleateinhibitor compound in an amount that is effective for providing lessthan 8 hours of bath life at 25° C.; yet does not have the same effectin an identical composition which is free of a fumarate or maleateinhibitor compound.

Our extensive experimentation indicates that Component (E) can be anyorganic or inorganic compound which is free of an inhibiting effect andhas a Hansen partial solubility parameter for hydrogen-bonding of 8.0 ormore, preferably 13-48. C. M. J. Hansen, Journal of Paint Technology.Volume 39, p. 104-105, (1967); and A. F. M. Barton, CRC Handbook ofSolubility Parameters and Other Cohesion Parameters, p. 153-160, CRCPress, Inc. are included herein by reference to disclose Hansen partialsolubility parameters for hydrogen-bonding and how to measure them.Preferred bath life extender compounds to be used as Component (E) inthe compositions of this invention have the above-noted Hansen value ofgreater than 8.0, preferably 13-48, and are free of steric hindrance inthe polar portion of the molecule.

General examples of preferred Component (E) include compounds whichcontain one or more primary or secondary alcohol groups, carboxylicacids (including compounds which yield carboxylic acids when exposed towater at room temperature), cyclic ethers, and water. Included in thisgroup are the primary and secondary alcohols; diols and triols, such asethylene glycol, propylene glycol and glycerine; partial ethers of diolsand triols, such as 2-methoxyethanol, 2-methoxypropanol and2-methoxyisopropanol; tetrahydrofuran; water and aqueous solutions ofmineral acids, alkalis and salts. Useful increases in the gel time of acurable composition of this invention have been observed for thesematerials.

Primary and secondary alcohols, preferably having fewer than 10 carbonatoms, have been found to be especially effective in delaying thegelling of a composition of this invention at room temperature and aremost preferred as Component (E). Examples thereof include methanol,1-butanol, 2-butanol, tetradecanol and other alkanols, such as ethanol,normal-and iso-propanol, iso-butanol, and the normal-, secondary- andiso-pentanols, -hexanols, -heptanols and -octanols; benzyl alcohol,phenol and other aromatic alcohols such as methylphenyl carbinol, and2-phenylethyl alcohol; allyl alcohol, cyclohexanol, etc. The particularchoice of a Component (E) from this group of materials can depend onsuch factors as volatility, toxicity, flammability and odor of theComponent (E) when considering the intended use of the composition. Apreferred bath life extender for most compositions of this invention isbenzyl alcohol.

The amount of Component (E) to be used in the compositions of thisinvention is not critical and is merely that amount that will provide alonger bath life for the composition than the bath life of an identicalcomposition, but containing no Component (E).

The amount of Component (E) that can be used in the compositions of thisinvention can be as high as 10 percent or more by weight, based on theweight of Component (A); however, there seems to be little advantage ofusing such a large amount since superior results, with respect to bathlife and cure time, can be obtained with a lesser amount. Preferably,the amount of Component (B) to be used in the compositions of thisinvention falls in the range of 0.1 to 5 percent, and most preferably 1to 3 percent, by weight, based on the weight of Component (A).

At the same time the weight ratio of Component (E) to Component (D) inthe compositions of this invention can have a value of from 20/1 to1/20, but, typically has a value of from 10/1 to 1/3, and preferably avalue of from 5/1 to 3/1.

The composition of this invention can contain any of the optionalcomponents commonly used in platinum group metal-catalyzed organosiliconcompositions, such as reinforcing and extending fillers, hydrocarbon andhalohydrocarbons free of aliphatic unsaturation, colorants, stabilizers,adhesion modifiers, adhesive-release modifiers, etc. In particular, thecoating compositions of this invention which have adhesive-releasingproperties can further comprise the well-known high release additives ofthe art. In this regard the disclosures of Sandford, U.S. Pat. No.4,123,604; Keil, U.S. Pat. No. 3,527,659; and Rivers-Farrell et al.,U.S. Pat. No. 4,611,042 are noted.

The compositions of this invention can be prepared by homogeneouslymixing Components (A), (B), (C), (D) and (E), and any optionalcomponents, using suitable mixing means, such as a spatula, a drumroller, a mechanical stirrer, a three-roll mill, a sigma blade mixer, abread dough mixer, and a two-roll mill.

The order of mixing Components (A) to (E) is not critical; however, itis highly preferred that Components (B) and (C) be brought together inthe presence of Components (D) and (E), most preferably in a finalmixing step. It is highly preferred to admix Component (D to C),followed by (A), then (E) and finally (B).

It is possible to mix all components in one mixing step immediatelyprior to using the curable composition. Alternatively, certaincomponents can be premixed to form two or more packages which isolates(C) from (B) and/or (A) and which can be stored for months, if desired,and then mixed in a final step immediately prior to the intended usethereof. For example Components (C), (D), (E), and a portion ofComponent (A), along with optional components such as fillers andsolvents, if desired, can be mixed to provide a first package andcomponent (B) and any remaining Component (A) can be mixed to provide asecond package. These two packages can then be stored until thecomposition of this invention is desired and then homogeneously mixed.It is also possible to place Components (B), (C), (D) and (E) in fourseparate packages and to place Component (A) in one or more of saidseparate packages and the four packages stored until needed.

The compositions of this invention have utility as formable compositionsto provide organosilicon articles such as O-rings, tubing, wire-coatingand gaskets; as encapsulant and sealant compositions; and as coatingcompositions, among others. They can be cured with heat and/or actinicradiation, such as electron beam radiation or ultraviolet lightradiation.

In another aspect the present invention relates to a process comprisingforming a liquid composition into a shaped article and subjecting thearticle to heat and/or actinic radiation for a period of time sufficientto convert the article to the solid state, said liquid compositioncomprising (A) an organosilicon compound having an average of at leasttwo curing radicals per molecule thereof selected from the groupconsisting of the hydroxy radical and olefinic hydrocarbon radicals, (B)an organohydrogensilicon compound containing an average of at least twosilicon-bonded hydrogen atoms per molecule thereof, the amounts ofComponents (A) and (B) being sufficient to provide a ratio of the numberof silicon-bonded hydrogen atoms to the number of silicon-bonded curingradicals of from 1/100 to 100/1, (C) a platinum group metal-containingcatalyst in sufficient amount to accelerate a curing reaction among saidsilicon-bonded curing radicals and said silicon-bonded hydrogen atoms,D) an inhibitor compound for said accelerated curing reaction in a totalamount sufficient to retard the curing reaction at room temperature butinsufficient to prevent said reaction at elevated temperature, and (E) abath life extender compound in a total amount sufficient to furtherretard the curing reaction at room temperature.

In the process of this invention the liquid curable composition is acomposition of this invention comprising Components (A), B), (C), (D)and (E) which are delineated above, including preferred embodimentsthereof. The amounts of Components (A), (B), (C), (D) and (E) that areused in the curable compositions of this invention are also as statedabove.

A significant characteristic of the liquid curable compositions of thisinvention is a long pot life whereby the viscosity of the compositiondoes not double in value over a period of several hours, therebyallowing an extended work time. Another significant characteristic ofthe process of this invention is the rapid curing that occurs when thecoated composition is heated to low elevated temperatures, such as 70°C.

Typically, the compositions of this invention will remain formable for 8hours or more at room temperature yet will cure fully, in thin section,when heated at 70° C. for 30 seconds. Higher heating temperatures, suchas up to 150° C., will provide correspondingly shorter curing times.

Thus the process of this invention comprises, in a particular aspect,forming at least a portion of the curable composition into an article 8hours or more after the curable composition has been prepared andheating the article at a temperature of about 70° to 150° C. for 30seconds or less. For example, a composition of this invention can beprepared and then used to coat a substrate for more than 8 hours and becurable in 30 seconds or less at 70° C. in thin section at any time inthe life of the bath. Alternatively, a composition of this invention canbe prepared, stored for more than 8 hours and then be formed into anarticle and be curable in 30 seconds or less at 70° C. in thin sectionat any time during the life of the bath.

In the process of this invention the liquid composition is formed intoan article having a desired shape, using any suitable means, such as bymolding, extruding, spreading, foaming, spraying, blowing, dripping,emulsifying, pouring, and the like. The liquid curable composition canhave any consistency, such as pourable, spreadable, gum-like orthixotropic, as long as it can be formed into a desired shape. Theformed article is then caused to cure to the solid, i.e., non-flowingstate, at least sufficiently to keep it in its desired shape.

The solid article can have any consistency in its fully cured state,such as a gel, an elastomer or a rigid body, depending upon the make-upof the curable composition and the curing conditions that were use inits preparation.

In the process of this invention the liquid compositions of thisinvention can be cured, partially or fully, by any suitable means. Forexample, as noted above, the curable composition can be heated, exposedto actinic radiation or heated and exposed to actinic radiation. Forshaped articles having a thin dimension, such as up to about 1/8 inch,any of the above-mentioned curing means can be used. For shaped articleshaving no thin dimension exposure to actinic radiation, particularlylow-energy radiation, alone may be insufficient to fully cure the shapedarticle.

By actinic radiation it is meant ultraviolet light; electron beamradiation; and alpha-, beta-, gamma- and x-rays. By heat it is meantinfrared radiation, hot-air, microwave radiation, etc. Of course actinicradiation is frequently accompanied by heat and the use of a combinationof the two falls within the scope and spirit of the present process.

In a preferred embodiment the present invention relates to a process forrendering the surface of a solid substrate less adherent to materialsthat normally adhere thereto, said process comprising (I) applying tosaid surface a coating of a liquid curable composition comprising (A) anorganosilicon compound having the formula XR₂ SiO(RXSiO)_(x) SiR₂ Xwherein R denotes a monovalent hydrocarbon or halohydrocarbon radicalfree of aliphatic unsaturation and having 1-20 carbon atoms, at least 50percent of all R radicals being methyl, X denotes a radical selectedfrom the group consisting of olefinic hydrocarbon radicals having from 2to 20 carbon atoms and R radicals, an average of at least two X radicalsper molecule of Component (A) being olefinic hydrocarbon radicals, x hasan average value sufficient to provide a viscosity at 25° C. of at least25 millipascal-seconds for the Component (A); (B) anorganohydrogensilicon compound having the formula YR₂ SiO(RYSiO)_(y)SiR₂ Y wherein R denotes a monovalent hydrocarbon or halohydrocarbonradical free of aliphatic unsaturation and having 1-20 carbon atoms, atleast 50 percent of all R radicals being methyl, Y denotes a hydrogenatom or an R radical, an average of at least two Y radicals per moleculeof Component (B) being hydrogen atoms, y has average values sufficientto provide a viscosity at 25° C. of from 1 to 100 millipascal-secondsfor the Component (B), the ratio of the amounts of (A) to (B) beingsufficient to provide from 0.5 to 2 silicon-bonded hydrogen atoms forevery silicon-bonded olefinic hydrocarbon radical; (C) aplatinum-containing compound in sufficient amount to accelerate thecuring reaction among said silicon-bonded curing radicals and saidsilicon-bonded hydrogen atoms; (D) an inhibitor compound having theformula R¹ (OD)_(h) O₂ CCH═CHCO₂ (DO)_(h) R¹, wherein each R¹ denotes,independently, a monovalent hydrocarbon radical, and h has a value of 0or 1, in a total amount sufficient to retard the curing reaction at roomtemperature but insufficient to prevent said reaction at elevatedtemperature, and (E) a bath life extender compound comprising a compoundbearing a primary or secondary alcohol radical, in a total amountsufficient to further retard the curing reaction of the mixture at roomtemperature; and (II) subjecting the applied coating to heat and/oractinic radiation for a period of time sufficient to cure the appliedcoating.

In the preferred process of this invention the coating process can beaccomplished by any suitable manner known in the art, such as byspreading, brushing, extruding, spraying, gravure, kiss-roll andair-knife.

In a preferred embodiment of the instant process the solid substrate isa flexible sheet material such as paper, polyolefin film andpolyolefin-coated paper or foil. Other suitable solid substrates thatcan be coated by the process of this invention include other cellulosicmaterials such as wood, cardboard and cotton; metallic materials such asaluminum, copper, steel and silver; siliceous materials such as glassand stone; and synthetic polymer materials such as polyolefins,polyamides, polyesters and polyacrylates. As to form the solid substratecan be substantially sheet-like, such as a peelable release liner forpressure sensitive adhesive; a fabric or a foil; or substantiallythree-dimensional in form.

After the liquid curable composition has been coated onto a substrate itis heated and/or irradiated with actinic radiation, as noted herein, tocure the liquid coating and to adhere it to the substrate.

In a preferred embodiment of the process of this invention a flexiblesheet material, such as paper, metal foil or tapestock, is coated with athin coating of the liquid curable composition, preferably in acontinuous manner, and the thus-coated material is then heated and/orirradiated to rapidly cure the coating, to provide a sheetlike materialbearing on at least one surface thereof an adhesive-releasing coating.The adhesive-releasing coating is subsequently brought into contact witha pressure sensitive adhesive, preferably in an in-line manner, to forman article having a peelable, i.e. releasable, adhesive/coatinginterface. Examples of such an article include, adhesive labels having apeelable backing, adhesive tape in roll form and adhesive packaged in astrippable container. The pressure sensitive adhesive can benon-silicone-based, such as the well-known acrylic or rubber types, orsilicone-based, such as the peroxide- or platinum-curablepolydiorganosiloxane-based adhesives.

The process of this invention is also applicable to adhesive materials,other than pressure sensitive adhesives. Examples of said adhesivematerials include foods, asphalt and gum polymers.

The following examples are disclosed to further teach, but not limit,the invention which is properly delineated by the appended claims. Allamounts (parts and percentages) are by weight unless otherwiseindicated. Viscosities were measured with a rotating spindle viscometer.

Bath life of a composition means the time interval required for thefreshly prepared composition to gel at room temperature.

Cure time for a composition means the time interval required for thecomposition, when coated onto S2S kraft paper, at a thickness of 1 poundper ream, to attain the no smear, no migration, no rub-off condition.

The no smear condition was determined by lightly streaking the coatingwith a finger and observing for the absence of haze in the streakedarea.

The no migration condition was determined by firmly adhering a common,pressure sensitive adhesive tape to the coating, removing the tape andfolding the removed tape together, adhesive surfaces to each other.Absence of migration of the coating to the tape was indicated by notingthat the doubled tape was as difficult to separate as unused tape sodoubled.

The no rub-off condition was determined by vigorously rubbing thecoating with the index finger and noting that the coating could not beremoved from the paper.

A 5-hexenyldimethylsiloxane-endblocked copolymer of dimethylsiloxaneunits and 5-hexenylmethylsiloxane units having the average formulaHexMe₁ SiO(Me₂ SiO)₁₅₁ (MeHexSiO)₃ SiMe₂ Hex, where Me denotes methyland Hex denotes CH₂ ═CHCH₂ CH₂ CH₂ CH₂ --, was prepared according toU.S. Pat. No. 4,609,574 by mixing cyclopolydimethylsiloxanes, thehydrolyzate of 5-hexenylmethyldichlorosilane, 5-hexenyl-endblockedpolydimethylsiloxane fluid, and KOH in a flask and heating to 150° C.for 5 hours. After cooling, the mixture was treated with carbon dioxidefor 30 minutes to neutralize the KOH. Fuller's Earth (5 g) was added andafter 24 hours, the mixture as filtered to yield the copolymer.

U.S. Pat. No. 4,609,574 is incorporated herein by reference to disclosethe details of how to prepare the copolymer delineated immediatelyabove, and other 5-hexenylsubstituted silicon compounds such asHexMeSiCl₂ and HexMe₂ SiCl and other polymers, such as the hydrolyzateof HexMeSiCl₂ and hexenyl-endblocked polydimethylsiloxane fluid.

EXAMPLES 1 TO 37

Several curable coating compositions were prepared by mixing, in theorder given, 100 g of the 5-hexenyl-endblocked copolymer of5-hexenylmethylsiloxane units and dimethylsiloxane units and, notedabove; an amount of an inhibitor, noted in Table I; an amount of a bathlife extender, noted in Table I; 2.0 g of a platinum catalyst (a solubleplatinum complex containing 0.67% platinum formed from chloroplatinicacid and divinyltetramethyldisiloxane); and 4.0 g of anorganohydrogenpolysiloxane having the average formula Me₃ SiO(Me₂ SiO)₁₂(MeHSiO)₂₈ SiMe₃.

Comparison compositions a-g were prepared identically except either theinhibitor or the bath life extender was omitted. These compositions arealso included in Table I.

The bath life at 25° C. (77° F.) of each of the example coatings andcomparison coatings were determined. In addition, the cure time at 82.2°C. (180° F.) of most of the freshly prepared compositions and of severalaged compositions were also measured. The results are summarized inTable I. The data of Table I are arranged in order of increasinginhibitor concentration and decreasing bath life at constant inhibitorconcentration.

These data show the following. Two parts of DEF (Exs. a-c) is needed toget adequate bath life in a composition of the art which does notcontain a bath life extender; however, the consequence is a drifting,albeit short, cure time. Using less DEF, in conjunction with certainpreferred bath life extenders (Exs. 3-15), provides improved bath lifeand a short, stable cure time, compared to an identical compositionexcept containing no bath life extender. Higher levels of DEF, inconjunction with preferred bath life extenders (Exs. 30-34), can be usedto restore original bath life, if desired, without the attendant curetime drift observed in the comparison compositions. Some improvement isavailable from other bath life extenders (Exs. 16-24); however, thesematerials are not preferred. Some polar materials (Exs. 25-28), althoughhaving high hydrogen-bonding partial solubility parameters, containamine groupings or steric hindrance and provide no improvement in thebath life of the composition.

With respect to MIM these data show that 1 part of MIM (Exs. d and e) isneeded to get adequate bath life in a composition of the art which doesnot contain a bath life extender; however, the consequence is long,albeit stable, cure time. Using less MIM, in conjunction with certainpreferred bath life extenders (Exs. 35-37), provides improved bath life,compared to an identical composition except containing no Component E),and a short, stable cure time.

                  TABLE I                                                         ______________________________________                                                           BATH  CURE TIME,                                                              LIFE, Sec. @ 82° C.                                 Extender*     Inhibitor* Hrs. @  IN-   ( )                                    Ex.  Ident     Amt    Ident Amt  25° C.                                                                       ITIAL Hour                             ______________________________________                                        1.   BzOH      .90    DEF   .10  <20    7    --                               2.   EGMME     .90    DEF   .10  <0.5   5    --                               3.   MeOH      .75    DEF   .25  >96    7    10(24)                           4.   1BuOH     .75    DEF   .25  >96    7    12(24)                           5.   2BuOH     .75    DEF   .25  >96    7    15(24)                           6.   BzOH      .75    DEF   .25  >96    7    12(24)                           7.   EGMME     .75    DEF   .25  >48   10    18(24)                           8.   H.sub.2 O .75    DEF   .25  >24   10    --                               9.   CDMSN     .75    DEF   .25  24    10    10(24)                           10.  Ac.sub.2 O                                                                              .75    DEF   .25  15    15    --                               11.  THF       .75    DEF   .25  13    10     20(3.5)                         12.  C.sub.14 OH                                                                             .75    DEF   .25  10    10     20(7.5)                         13.  5% H.sub.2 .sup.+                                                                       2.0    DEF   .25  10    --    --                               14.  5% OH.sup.-                                                                             2.0    DEF   .25  10    --    --                               15.  5% H.sup.+                                                                              2.0    DEF   .25  10    --    --                               16.  EG        .75    DEF   .25  2     15    --                               17.  PDMS      9.75   DEF   .25  1.8   rub-off                                                                             --                               18.  Glycer    .75    DEF   .25  1.5   15    --                               19.  HOAc      .75    DEF   .25  1.5   10     15(1.1)                         20.  tBuOH     .75    DEF   .25  <1.5   7    --                               21.  EHA       .75    DEF   .25  1.0   10    --                               22.  ECNM      .75    DEF   .25  1.0    7    --                               23.  C.sub.3 H.sub.6 O                                                                       2.0    DEF   .25  0.8    8    --                               24.  EtOAc     .75    DEF   .25  0.5    7    --                               25.  Ph.sub.2 O                                                                              .75    DEF   .25  0.33  15    --                               26.  PhCHO     .75    DEF   .25  0.3   15    --                               27.  C.sub.5 H.sub.5 N                                                                       .75    DEF   .25  0.25  10    --                               28.  DMAPA     .75    DEF   .25  <1    --    --                                                                min.                                         29.  EHA       .25    DEF   .75  5     10    --                               30.  EGMME     .26    DEF   .74  >168  10    20(24)                           31.  BzOH      .26    DEF   .74  >168  10    20(27)                           32.  MeOH      2.4    DEF   .99  >168  12    25(7)                            33.  BzOH      9.65   DEF   .95  144   12    25(7)                            34.  MeOH      9.65   DEF   .95  96    12    25(7)                            35.  BzOH      .95    MIM   .05  <1     7    --                               36.  BzOH      .90    MIM   .10  3     17    17(2)                            37.  BzOH      .80    MIM   .20  >72   30    30(17)                           a.   None      --     DEF   .25  0.3    7    --                               b.   None      --     DEF   1.0  1     10    --                               c.   None      --     DEF   2.0  >168  12    40(7)                            d.   None      --     MIM   .20  0.5   30    --                               e.   None      --     MIM   1.0  >168  75    80(24)                           f.   ECNM      1.0    None  --   0     --    --                               g.   BzOH      1.0    None  --   0     --    --                               ______________________________________                                         *See Table II for explanation of Ident.                                  

                  TABLE II                                                        ______________________________________                                        Component                Hydrogen Bonding                                     Identity                 Partial Solubility                                   Code     Compound        Parameter                                            ______________________________________                                        Ac.sub.2 O                                                                             Acetic anhydride                                                                              10.2                                                 1BuOH    1-Butanol       15.8                                                 2BuOH    2-Butanol       14.5                                                 tBuOH    t-Butanol       16.0                                                 BzOH     Benzyl alcohol  13.7                                                 C.sub.3 H.sub.6 O                                                                      Acetone         7.0                                                  C.sub.5 H.sub.5 N                                                                      Pyridine        5.9                                                  C.sub.14 OH                                                                            Tetradecanol    --                                                   CDMSN    Cyclodimethyl-  --                                                            polysilazane                                                         DEF      Diethyl fumarate                                                                              --                                                   DMAPA    Dimethylamino-  --                                                            propylamine                                                          ECNM     Ethyl cinnamate 4.1                                                  EG       Ethylene glycol 26.0                                                 EGMME    Ethylene glycol-                                                                              16.4                                                          monomethyl ether                                                     EHA      Ethylhexanoic acid                                                                            8.2                                                  EtOAc    Ethyl acetate   7.2                                                  Glycer   Glycerine       29.3                                                 5% H.sup.+                                                                             Aqueous HCl     --                                                   HOAc     Acetic Acid     13.5                                                 H.sub.2 O                                                                              Water           48.0                                                 5% H.sub.2 .sup.++                                                                     Aqueous H.sub.2 SO.sub.4                                                                      --                                                   MeOH     Methanol        22.3                                                 MIM      Bis-(2-methoxyiso-                                                                            --                                                            propyl) maleate                                                      5% OH.sup.-                                                                            Aqueous NaOH    --                                                   PDMS     Polydimethylsiloxane                                                                          --                                                   Ph.sub.2 O                                                                             Diphenyl ether  --                                                   PhCHO    Benzaldehyde    5.3                                                  THF      Tetrahydrofuran 8.0                                                  ______________________________________                                    

EXAMPLES 38 TO 42

Five coating composition of this invention (Compositions 38 to 42) wereprepared by mixing, in the order given, 100 g of a vinyl-endblockedcopolymer of dimethylsiloxane units and vinylmethylsiloxane units havingthe average formula ViMe₂ SiO(Me₂ SiO)₁₅₁ (MeViSiO)₃ SiMe₂ Vi where Medenotes methyl and Vi denotes CH₂ ═CH-- (prepared by mixingcyclopolydimethylsiloxanes, cyclopolymethylvinylsiloxanes,vinyl-endblocked polydimethylsiloxane fluid, and KOH in a flask andheating as was done for the hexenyl-substituted polymer noted above),2.0 g of the platinum catalyst of Examples 1 to 37, an amount of diethylfumarate, noted in Table III; an amount of benzyl alcohol, noted inTable III; and 4.0 g of the methylhydrogenpolysiloxane crosslinker ofExamples 1 to 37. For comparison, a coating compositions (Compositionsh) was identically prepared, except containing no benzyl alcohol.

The bath life at 25° and 40° C., and cure time at 82.2° C. for freshlyprepared and aged samples, of each of the example coatings andcomparison coatings were determined and the results are summarized inTable III.

                  TABLE III                                                       ______________________________________                                                            CURE TIME                                                                     Sec. @ 82° C.                                      BzOH,*    DEF*    BATH LIFE   IN-                                             Ex.  pph      pph     25° C.                                                                       40° C.                                                                       ITIAL  ( ) Hour                             ______________________________________                                        38.  0.75     0.25     24   --    20      55(16)                              39.  2.00     2.00    >48   >36   20     55(5)                                40.  4.00     2.00    >48   >36   20     45(5)                                41.  6.00     2.00    >48    36   20     35(5)                                42.  8.00     2.00    >48   >36   20     40(5)                                h.   --       2.00    >48    24   20     70(5)                                ______________________________________                                         *BzOH is benzyl alcohol. DEF is diethyl fumarate.                        

EXAMPLE 43

This example is presented to illustrate a utility of the composition ofthis invention.

A curable coating composition of this invention was prepared by mixing,in the order given, 100 g of the 5-hexenyl-endblocked copolymer of5-hexenylmethylsiloxane units and dimethylsiloxane units, noted above; amixture of 0.72 g of diethyl fumarate and 1.95 g of a platinum catalyst(a soluble platinum complex containing 0.67% platinum formed fromchloroplatinic acid and divinyltetramethyldisiloxane); 0.31 g of benzylalcohol; and 4.0 g of an organohydrogenpolysiloxane having the averageformula Me₃ SiO(Me₂ SiO)₁₂ (MeHSiO)₂₈ SiMe₃.

The viscosity of the coating at 40° C. (104° F.) was found to range from365 to 408 mPa.s (centipoise) over an 8 hour period. The cure time ofthe freshly prepared composition was found to be 15 seconds, 5 secondsand less than 5 seconds at 82.2° C. (180° F.), 115.5° C. (240° F.) and148.9° C. (300° F.), respectively.

For comparison a compositions (i) of the prior art was prepared bymixing, in the order given, 100 g of the 5-hexenyl-endblocked copolymerof 5-hexenylmethylsiloxane units and dimethylsiloxane units, notedabove; 0.83 g of bis(2-methoxyisopropyl) maleate; 1.95 g of a platinumcatalyst (a soluble platinum complex containing 0.67% platinum formedfrom chloroplatinic acid and divinyltetramethyldisiloxane); and 4.0 g ofan organohydrogenpolysiloxane having the average formula Me₃ SiO(Me₂SiO)₁₂ (MeHSiO)₂₈ SiMe₃.

The viscosity of the comparison coating at 40° C. (104° F.) was found torange from 378 to 698 mPa.s (centipoise) over an 8 hour period. The curetime of the freshly prepared composition was found to be 50 seconds, 15seconds and less than 5 seconds at 82.2° C. (180° F.), 115.5° C. (240°F.) and 148.9° C. (300° F.), respectively.

The freshly prepared compositions were coated onto 54 pound paper andsamples of the coated paper were heated at 180°, 240° or 300° F. forvarious lengths of time and the thus-cured coatings were laminated,in-line, with an acrylic adhesive (GMS-263; Monsanto, St. Louis, Mo.).The adhesive solution was applied to the coatings at a wet thickness of3 mils using a drawdown bar. The applied adhesive was air-dried at roomtemperature for one minute, heated at 70° C. for one minute and thecooled to room temperature for one minute. A sheet of 60 pound mattelitho was applied to the dried adhesive and the resulting laminates werepressed with a 4.5 pound rubber-coated roller. The test laminates werethen aged at room temperature for 1 day and cut into 1-inch strips.Adhesive release testing was done by pulling the substrate/coating fromthe matte/adhesive of the 1-inch strips at an angle of 180 degrees andat a rate of 10 meters per minute. The force needed to separate theadhesive/coating interface was noted several times during the separationand adhesive release was noted as an average of the several readings.

The release values, listed in Table IV, show that the compositions ofthis invention are more efficient in an in-line process of adhesivelamination than a composition of the prior art. In other words, acomposition of the prior art, noted for its utility as a release coatingfor receiving an acrylic adhesive, in-line, requires a heating time of130 seconds at 180° F. to provide a laminate having a release which issimilar to the composition of this invention which was heated for only50 seconds. This advantage is found at higher temperatures as well,albeit to a lesser degree.

                  TABLE IV                                                        ______________________________________                                        Cure Conditions                                                                              Adhesive Release g/in.                                         Seconds/°F.                                                                           Comparison (i)                                                                            Example 43                                         ______________________________________                                        50/180         Tear        133                                                90/180         210         90                                                 130/180        145         65                                                 20/240         95          80                                                 40/240         58          50                                                 80/240         50          40                                                 10/300         65          60                                                 20/300         56          53                                                 40/300         40          30                                                 ______________________________________                                    

EXAMPLES 49 TO 50

Several curable coating compositions were prepared by mixing 100 g ofthe 5-hexenyl-endblocked copolymer of 5-hexenylmethylsiloxane units anddimethylsiloxane units and, noted above; an amount of an inhibitor,noted in Table V; an amount of a bath life extender, noted in Table V;2.0 g of a platinum catalyst (a soluble platinum complex containing0.67% platinum formed from chloroplatinic acid anddivinyltetramethyldisiloxane); and an amount of anorganohydrogenpolysiloxane, noted in Table V, having the average formulaMe₃ SiO(Me₂ SiO)₁₂ (MeHSiO)₂₈ SiMe₃ (B-1); or Me₃ SiO(MeHSiO)₃₅ SiMe₃(B-2); or a 50/50 mixture (B-3) of organohydrogenpolysiloxanes havingthe formulae Me₃ SiO(Me₂ SiO)₃ (MeHSiO)₅ SiMe₃ and Me₃ SiO(MeHSiO)₃₅SiMe₃.

Comparison compositions j-1 were prepared identically except either thebath life extender or the crosslinker was omitted. These compositionsare also included in Table V.

The compositions were coated onto paper and exposed to ultravioletlight, using a two-lamp PPG coater. The maximum web speed that permitteda full cure of the composition was measured and converted to exposuretime in seconds. The results are summarized in Table V. These data showthat the compositions of this invention are readily curable by UV.

The UV-induced cure rate is independent of the identity of thecrosslinker (Exs. 44-46 and 1) or the amount of bath life extender (Exs.46 vs 47; 48 vs j and 50 vs k). The UV-induced cure rate is dependent onthe amount and type of inhibitor (Exs. 47-50).

                  TABLE V                                                         ______________________________________                                                               CROSS-                                                 Extender*   Inhibitor* LINKER    CURE TIME                                    Ex.  Ident   Amt    Ident Amt  Ident                                                                              Amt  Seconds                              ______________________________________                                        44.  BzOH    .40    DEF   .80  B-3  3.6  0.6                                  45.  BzOH    .40    DEF   .80  B-2  3.0  0.7                                  46.  BzOH    .40    DEF   .80  B-1  4.0  0.6                                  47.  BzOH    1.00   DEF   .80  B-1  4.0  0.6                                  48.  BzOH    3.00   DEF   3.0  B-1  4.0  1.3                                  49.  BzOH    1.00   MIM   .80  B-1  4.0  1.5                                  50.  BzOH    1.60   MIM   .40  B-1  4.0  1.3                                  j.   None    --     DEF   3.0  B-1  4.0  1.3                                  k.   None    --     MIM   .40  B-1  4.0  1.3                                  1.   BzOH    .40    DEF   .80  --   0.0  >10                                  ______________________________________                                         *See Table II for explanation of Ident.                                  

EXAMPLE 51

A coating composition of this invention was prepared by mixing 100 g ofthe vinyl-endblocked copolymer of dimethylsiloxane units andvinylmethylsiloxane units noted in Examples 38-42, 2.0 g of the platinumcatalyst of Examples 1 to 37, 0.8 g of diethyl fumarate, 1 g of benzylalcohol, and 5.3 g of the methylhydrogenpolysiloxane crosslinker ofExample 44. The bath life at 25° and UV-cure time for the compositionwere determined to be >168 hours and 0.8 seconds, respectively.

EXAMPLE 52

The freshly prepared composition of Example 46 was coated onto 54 poundpaper and on polypropylene film and the samples were exposed to UVlight, using a two-lamp PPG coater. The coating on the polypropylenefilm cured at 115 feet/minute while the coating on paper cured at 135feet/minute. The thus-cured coatings were laminated, in-line, with anacrylic adhesive (GMS-263; Monsanto, St. Louis, Mo.) or with NationalStarch 36-6149 SBR adhesive. The adhesive solution was applied, andsamples were prepared and tested for adhesive release, as noted above.

The release values, listed in Table VI, show that the compositions ofthis invention can be rapidly and thoroughly cured by UV light in anin-line process to provide liner for the release of various types ofadhesives.

                  TABLE VI                                                        ______________________________________                                                     Adhesive Release g/in.                                           Substrate Adhesive 1 Day     2 Days                                                                              14 Days                                    ______________________________________                                        Paper     Acrylic  111.1     68.1  62.8                                       Paper     SBR      45.9      39.8  39.7                                       PP        Acrylic  22.0      18.4  15.1                                       PP        SBR      12.9      11.3  10.5                                       ______________________________________                                    

EXAMPLES 53-58

Several compositions of this invention, identical to that of Example 46except containing various amounts and types of platinum-containingcatalysts, were prepared. Compositions 53-57 contained the catalyst ofCompositions 1-37. Composition 58 contained H₂ PtCl₆.6H₂ O. The results,listed in Table VII show that the UV-initiated cure rate and the bathlife of the compositions of this invention are dependent upon the typeand concentration of the catalyst component (C).

                  TABLE VII                                                       ______________________________________                                               CATALYST     CURE TIME   BATH LIFE                                     Ex.    Amt          Seconds     Days @ 25° C.                          ______________________________________                                        53     0.4          1.3         >7                                            54     0.8          0.9         >7                                            55     1.6          0.9         >7                                            56     2.0          0.6         >7                                            57     3.0          0.6         2-5                                           58     2.0          3.0         >7                                            59     2.0          0.8         >7                                            60     2.0          3.0         >7                                            ______________________________________                                    

EXAMPLES 59 and 60

Compositions 59 and 60, identical to those of Examples 56 and 58,respectively, were prepared, except using 88 g of the polymer used inthe compositions of Examples 38-42 instead of the 100 g ofhexenyl-substituted polymer. The UV-initiated cure rate and the bathlife of these compositions are also listed in Table VII.

EXAMPLE 61

The composition of Example 52 was coated onto polypropylene film andexposed to 2 megarads of electron beam radiation in air or in nitrogen.Fully cured coatings were obtained.

EXAMPLES 62 and 63

Three compositions were prepared as disclosed in Examples 1-37, exceptusing either 1 part of crude ethylphenyl fumarate (Example 62), or 1part of pure ethylphenyl fumarate (Comparison), or 1 part of a mixtureof pure ethylphenyl fumarate and phenol (Example 63) as the cure controlcomponent. Crude ethylphenyl fumarate was prepared by reacting excessphenol with the monoethyl ester of fumaryl chloride in the presence ofbase. The composition containing crude ethylphenyl fumarate had a roomtemperature bath life of more than 10 days and a non-drifting cure timeof 20 seconds at 180° F. The composition containing pure ethylphenylfumarate had a room temperature bath life of less than 1 day. Thecomposition containing the mixture of pure ethylphenyl fumarate andphenol had the performance of the composition containing crudeethylphenyl fumarate.

That which is claimed is:
 1. A process for rendering the surface of a solid substrate less adherent to materials that normally adhere thereto, said process comprising(I) applying to said surface a coating of a liquid curable composition comprising(A) an organosilicon compound having the formula XR₂ SiO(RXSiO)_(x) SiR₂ X wherein R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation and having 1-20 carbon atoms, at least 50 percent of all R radicals being methyl, X denotes a radical selected from the group consisting of olefinic hydrocarbon radicals having from 2 to 20 carbon atoms and R radicals, an average of at least two X radicals per molecule of Component (A) being olefinic hydrocarbon radicals, the subscript x has an average value sufficient to provide a viscosity at 25° C. of at least 25 millipascal-seconds for the Component (A); (B) an organohydrogensilicon compound having the formula YR₂ SiO(RYSiO)_(y) SiR₂ Y wherein R denotes a monovalent hydrocarbon or halohydrocarbon radical free of aliphatic unsaturation and having 1-20 carbon atoms, at least 50 percent of all R radicals being methyl, Y denotes a hydrogen atom or an R radical, an average of at least two Y radicals per molecule of Component (B) being hydrogen atoms, the subscript y has average values sufficient to provide a viscosity at 25° C. of from 1 to 100 millipascal-seconds for the Component B), the ratio of the amounts of (A) to (B) being sufficient to provide from 0.5 to 2 silicon-bonded hydrogen atoms for every silicon-bonded olefinic hydrocarbon radical; (C) a platinum-containing compound in sufficient amount to accelerate the curing reaction among said silicon-bonded curing radicals and said silicon-bonded hydrogen atoms; (D) an inhibitor compound for said accelerated curing reaction having the formula R¹ (OD)_(h) O₂ CCH═CHCO₂ (DO)_(h) R¹, wherein R¹ denotes, independently, a monovalent hydrocarbon radical having from 1 to 10 carbon atoms, each D denotes, independently, an alkylene radical having from 2 to 4 carbon atoms, and the subscript h has a value of 0 or 1, in a total amount sufficient to retard the curing reaction at room temperature but insufficient to prevent said reaction at elevated temperature; and (E) a bath life extender compound selected from the group consisting of compounds containing at least one primary or secondary alcohol radical, carboxylic acids, compounds which yield carboxylic acids when exposed to water at room temperature, cyclic ethers, and water, in a total amount sufficient to further retard the curing reaction at room temperature; and (II) subjecting the applied coating to heat and/or actinic radiation for a period of time sufficient to cure the applied coating.
 2. A process in accordance with claim 1 wherein at least a portion of the composition is applied to a substrate more than 8 hours after the components thereof were mixed and the applied coating is heated at a temperature of from 70° to 150° C. for 30 seconds or less.
 3. A process in accordance with claim 1 wherein Component (A) has the formula XMe₂ SiO(Me₂ SiO)_(b) (MeXSiO)_(d) SiMe₂ X wherein Me denotes methyl, X denotes a radical selected from the group consisting of olefinic hydrocarbon radicals having from 2 to 20 carbon atoms and methyl radicals, an average of at least two X radicals per molecule of Component (A) being olefinic hydrocarbon radicals, the subscripts b and d have average values of zero or more, and the sum of b plus d has a value sufficient to provide a viscosity at 25° C. of at least 25 millipascal-seconds for the Component (A) and Component (B) has the formula YMe₂ SiO(Me₂ SiO)_(p) (MeYSiO)_(q) SiMe₂ Y wherein Y denotes a hydrogen atom or a methyl radical, an average of at least two Y radicals per molecule of Component (B) being hydrogen atoms, the subscripts p and q have average values of zero or more, the sum of p plus q has a value sufficient to provide a viscosity at 25° C. of from 1 to 100 millipascal-seconds for the Component B), the ratio of the amounts of (A) to (B) being sufficient to provide from 0.5 to 2 silicon-bonded hydrogen atoms for every silicon-bonded olefinic hydrocarbon radical; Component (C) is a vinyl-siloxane complex of chloroplatinic acid; Component (D) is a fumarate having the formula R¹ (OD)_(h) O₂ CCH═CHCO₂ (DO)_(h) R¹ ; and Component (E) is a primary or secondary alcohol.
 4. A process according to claim 3 wherein the substrate is a flexible sheet material.
 5. A process according to claim 4 wherein the flexible sheet material is paper.
 6. A process according to claim 4 further comprising (III) releasably adhering a pressure sensitive adhesive composition to the cured applied coating.
 7. A process in accordance with claim 3 wherein Component (A) has the formula HexMe₂ SiO(Me₂ SiO)_(b) (MeHexSiO)_(d) SiMe₂ Hex, wherein Hex denotes CH₂ ═CHCH₂ CH₂ CH₂ CH₂ --, Component (B) has the formula Me₃ SiO(Me₂ SiO)_(p) (MeHSiO)_(q) SiMe₃, Component (D) is diethyl fumarate and Component (E) is benzyl alcohol.
 8. A process in accordance with claim 3 wherein Component (A) has the formula ViMe₂ SiO(Me₂ SiO)_(b) (MeViSiO)_(d) SiMe₂ Vi, wherein Vi denotes CH₃ ═CH--, Component (B) has the formula Me₃ SiO(Me₂ SiO)_(p) (MeHSiO)_(q) SiMe₃, Component (D) is diethyl fumarate and Component (E) is benzyl alcohol. 